Security – What does this strange network/subnet mask mean

Maybe not the best design:
Are you sure that is the route you want to go? It should work fine, but then you are using the entire 192.168.x.x network for one broadcast domain. That is going to give you 65534 hosts. If your company grows, you are going to have re-subnet the entire network again or start using 10.x.x.x or 172.16-172.31.x.x address.

A More Standard Way to Approach it:
I think a more normal approach be to use a subnet per location, or office floor, etc.

1. Start with how many machines might end up at each location and then maybe bump up to the subnet above that.

For Example:
So if you think you might have 254 devices on the network per area, bump it up to 255.255.252.0, the next subnet up. This will give you a host range of 192.168.0.1-192.168.3.254. Then when it becomes time to expand, the next range using the same subnet mask would be 192.168.4.1 to 192.168.7.254.

A Simple Way:
A simple way if your office is small, would be just to set the DHCP range to something like 192.168.0.1-150, and then use the rest of the IPs in that address space for static assignment. Your DHCP server should have the option to specify a host range to hand out that doesn't line up with network mask. And if it only works by subnet masks, you could always cut the subnet in half with a mask of 255.255.255.128.

A Good Subnetting Read:
I recommend reading Evan's answer to How does Subnetting Work, and How do you do it?.

As I see, this question is 3-years old, but I decided to put an answer as it might be useful to someone who visit this page, some day.

This question is about PBR (policy-based routing), also known as routing based on source address. The thing is, this stuff is "officially" not supported by the ASA. BUT, there's a trick with NAT that can be used to achieve similar results. It's called Identity NAT, also know as same-address translation.

In this case this would look like this:

sysopt noproxyarp newlink

static (newlink,newlink) 0.0.0.0 0.0.0.0 netmask 0.0.0.0

This is saying: when ANY IP (0.0.0.0/0) comes on interface newlink, put it back on interface newlink while translating it to itself (0.0.0.0). So no NAT really happens but we are saying what will be the output interface. This routing table override is happening because when using identity NAT, the NAT process does some partial routing based on the "translated" interface. The sysopt noproxyarp newlink command is needed, because otherwise the ASA will start reposponding to ARP requests (proxy-ARP) for any destination address arriving the "newlink" interface. All of this is pre-8.3 ASA OS syntax.

Post-8.3 syntax is like this:

sysopt noproxyarp newlink

nat (newlink,newlink) source static any any